The Syrphidae of Puerto Rico1'2 H. S. Telford3-* One cannot state with certainty when the first syrphid was collected from Puerto Rico and adjacent islands. Fabricius described a number of 1 Manuscript submitted to Editorial Board October 30, 1972. 2 Scientific paper number 3914. College of Agriculture Research Center, Washing­ ton State University, Pullman, Washington. Work was conducted under Project No. 0046. 3 Professor and Entomologist, Department of Entomology, Washington State University; Visiting Scientist, Department of Entomology, Agricultural Experiment Station, Mayagiiez Campus, Uío Piedras, Puerto Rico, September 1968-March 1969. This study was made possible by financial support from the Department of En­ tomology, Agricultural Experiment Station, Mayagiiez Campus, University of Puerto Rico, Río Piedras. I wish to thank Dr. L. P. R. F. Martorell, formerly Chairman, Department of Entomology, Agricultural Experiment Station, especially for his support and aid in all aspects of the project. Mr. Silverio Medina Gaud, Associate Entomologist, Agricultural Experiment Station, was of considerable help. He ac­ companied me on almost all field trips, assisted in sorting and preparing the material and made valuable field trips on his own. Dr. J. R. Vockeroth, Entomology Research Institute, Ottawa, Canada, verified many determinations and offered advice on nomenclatural problems. Others who materially aided in the loan of specimens, verified determinations or in other ways were: Dr. George Drury, U.S. Atomic Energy Commission, El Verde-Caribbean National Forest, Puerto Rico; Dr. Y. S. Sedman, Western Illinois University; Dr. L. V. Knutson, Systematic Entomology Laboratory, Agricultural Research Service, United States Department of Agriculture; Dr. P. W. Wygodzinsky, American Museum of Natural History; Dr. John Lawrence, Museum of Comparative Zoology; Dr. Howard Weems, Florida Department of Agriculture; Dr. Frank M. Hull, University of Mississippi; Dr. M. T. James, Washington State University; Mr. Harold Oldroyd and Mr. Kenneth G. V. Smith, British Museum of Natural History; Dr. II. Frankhanel, Deutsches Entomologisches Institut; and Dr. George Miskimen, Entomologist, formerlj' with the Entomology Pioneering Research Laboratory, now with the Department of Biology, Mayagiiez Campus, University of Puerto Rico. Drs. J. R. Vockeroth, William J. Turner, and L. V. Knutson reviewed the manuscript. Miss Lynda L. Richards prepared the illustrations. 4 While this paper was in galley proof, the important and comprehensive publica­ tion, "A contribution to a generic revision of the Neotropical Milesinae (Diptera: Syrphidae)", Arq. Zool. S. Paulo 23(2): 73-215, 1972 by F. Cristian Thompson came to my attention. Although the milesines comprise only 17 of the 58 species occurring in Puerto Hico, this group is widely represented in the Neotropics, especially South and Central America. Any serious student of Neotropical Syrphidae should refer to this valuable paper. Dr. Thompson has made some drastic nomenclatural changes in some groups. For example, Copesh/lum Macquart is now recognized for all of the New World species of Vohicella Geoffroy except bombylans (L.) and Erislalis Latreille is partitioned into Erislalis s.s., Eosenslalis Kanervo and Palpada Macquart. Good generic keys have long been needed for the Neotropical genera and Dr. Thompson's contribution fills this void. 217 218 JOURNAL OF AGRICULTURE OF UNIVERSITY OF PUERTO RICO species from the West Indies as early as 1781 (35). Von Roeder (7S) pub­ lished the first extensive list of Díptera from Puerto Rico, including several species of syrphids, based upon the collections of the Cuban naturalist, Dr. Juan Gundlach. Later workers who have contributed to our knowledge of the Puerto Rican syrphid fauna are Curran, Fluke, and especially Hull. Four publications are especially important: Curran (16) "Insects of Porto Rico and Virgin Islands"; Wolcott (107) "The Insects of Puerto Rico"; Fluke (45,46) "Catalog of the Family Syrphidae in the Neotropical Re­ gion", and Maldonado and Navarro (72) "Additions and Corrections to Wolcott's 'Insects of Puerto Rico' ". As a result of synonymy, additional records and descriptions of four new species (Baccha (Ocyptamus) medina, B. (Ocyptamus) vockerothi, B. (Baccha) marotelli, and B. (Baccha) neopawicornis), 58 species are now recorded from the island. Undoubtedly this list could be substantially increased if exten­ sive collecting were continued. The present study was based largely upon the collection of the Department of Entomology at the Agricultural Ex­ periment Station, University of Puerto Rico, Río Piedras, P.R. and to a lesser extent, on the collection of the Department of Biology, Mayagücz Campus, Maj'agüez, P.R. The collection at the Department of Entomology, Agricultural Experi­ ment Station, in Río Piedras, was substantially increased by intensive Malaise trapping by myself and Mr. Silverio Medina Gaud during a 6- month period from September 1968 to March 1969. The island was sys­ tematically collected and most of the typical ecological communities were sampled. Additional records were obtained from Dr. George Drury of the U.S. Atomic Energy Commission, El Verde, Puerto Rico, from the collections of the U.S. National Museum of Natural History (USNM), the American Museum of National History (AMNH), and from the Canada National Collection (CNC). Unless otherwise stated all specimens arc deposited in the collections of the Department of Entomology, Agricultural Experi­ ment Station, University of Puerto Rico, Río Piedras, or in the M. T. James Entomological Collection, Washington State University, Pullman, Washington. ECONOMIC IMPORTANCE Of the 58 species herein recorded from the island, 41 may be aphidopha- gous. These include representatives of the genera Mesograpta, Baccha, Allograpta, Xanthandrus, and Parapenium. All of these except Parapenium belong to the Syrphinae. The remainder belong to the Milesiinae. The species of Mesograpta and Baccha outnumber, by far, all the other species of the family occurring on the island. It has long been assumed that most SYRPHIDAE OF PUERTO RICO 219 of the subfamily Syrphinae arc aphidophagous; unfortunately, life history studies have been undertaken on only a few species. When more is know n we may find that some are facultative predators or that some subsist en­ tirely upon plant food. For example, the well-known predator Allograpta obliqua can live on plant food during its larval stages and Mesograpia polita has been reared on corn pollen. Representatives of other related genera, Melanosloma and Plalycheirus, (not occurring in Puerto Rico), can ap­ parently survive on decomposing plant material as well as on insect prey. Aphidophagous syrphids are often extremely beneficial in suppressing aphid outbreaks. A European species, Syrphus corollae, was observed devouring 680 aphids during its larval development (Láska, 61). The use of these predators should be more widely investigated. Unlike other insect predators such as coccinellids, syrphids produce and distribute large numbers of eggs over extensive areas even though prey density may be low. They are excellent fliers and range over extensive areas, thus can select favorable oviposition sites with developing aphid colonies (Sundy, 91). This is a considerable advantage in preventing aphid outbreaks. KEY TO GENERA OF SYRPHIDAE OCCURRING IN PUERTO RICO 1. r-m crossvein situated before middle of cell M2 (fig. 1) 2 r-m crossvein at or beyond middle of cell M2 10 2. Humerus bare; arista usually bare; face tuberculate, usually at least partly 3'ellow; usually with yellow abdominal bands; legs slender 6 Humerus pilose; either small (5-6 mm.), bluish-black with bare arista, or larger more robust species with plumose arista and face protuding downward 3 3. Mi + 2 not recurrent distally; face protruding downward, arista moderately to densely plumose 4 Mi+2 not recurrent; face not protracted, arista bare; small (5-6 mm.), bluish-black species with short white pile... .Parapenium 4. Large (8-19 mm.), brightly metallic-green, blue or bluish-green or mostly black 5 Smaller (5-6 mm.), brown and black or black and yellow Volucella 5. Brightly metallic-green, blue or bluish-green; face with tubercle each side of median tubercle; (8-12 mm.) Ornidia Mostty black; basal half of wing blackish or dark-brown on anterior half; face without tubercules; large robust species; (16-19 mm.) Volucella 6. Abdomen slender, spatulate Baccha Abdomen broader with parallel sides 7 220 JOURNAL OF AGRICULTURE OF UNIVERSITY OF PUERTO RICO 7. Mesonotum with anterior collar of longer hairs Baccha Mesonotum without longer hairs anteriorly 8 8. Face and scutellum entirely black or dark blue Xanthandrus Face and scutellum partly or entirely yellow 9 9. Face vertical, with obscure tubercle; mesonotum with disc shining black Allograpta Face distinctly protruding below; mesonotum with cinereous stripe or stripes on disc Mesograpta 10. Vein R.i+5 deeply bent into cell R5; hind femur not enlarged 11 Vein Ri+5 straight or nearly so; hind femur enlarged, spinose along lower surface 12 11. Yellow or gray markings on mesonotum composed of dense tomen- tum Meromacrus FIG. 1.—Wing of Erislalis showing venation. Yellow or gray markings of mesonotum due to either ground color or to pollen Eristalis 12. Face concave in profile, at most weakly carínate; metasternum pilose Neplas Face not concave, strongly carínate; metasternum pubescent or bare Crepidomyia Genus Allograpta Osten Sacken Allograpta Osten